In communications networks, data is often transported on communications links using a variety of communications protocols. Often there arises a need to gather data acquired from nodes via different communications links using different protocols, and share that data over a common communications links using another protocol. To address this need, devices that enable cross-connection (also referred to as cross-link) between differing protocols has been developed. Examples of such devices include the WorldDSL model WD92xGN and WD92xGL G.SHDSL line units from ADC, which in one configuration when configured as a cross-connection, enable data received from G.703, Nx64k, and Ethernet protocol interfaces on one side of the cross-connection to be communicated on a G.703 protocol interface on the other side of the cross-connection. In another configuration, such devices can be configured to enable data received from a G.703 protocol interface on one side of the cross-connection to be communicated via G.703, Nx64k, and Ethernet protocol interfaces on the other side.
One standard method of flagging that a fault condition exists on an interface port is with an alarm indication signal (AIS). One problem that arises in the use of such cross-connections concerns the communication of fault conditions affecting one side of the cross-connection to network equipment connected to the other side of the cross-connection without interfering with data communications from any non-faulted ports. For example, in the above mentioned configuration where data received from G.703, Nx64k, and Ethernet protocol interfaces on the first side of a cross-connection are communicated on a G.703 protocol interface on the second side of the cross-connection, if a fault is detected on the Nx64K port on the first side, initiating an AIS signal on the G.703 port on the second side would interfere with the continued transport of data received on the non-faulted G.703 and Ethernet first side ports via the G.703 second side port.
For the reasons stated above and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for improved systems and methods for communicating faults across a communications network cross-connect.